Characterization of fancy yarn

ABSTRACT

According to the method for characterizing fancy yarn, at least one characteristic of the fancy yarn is scanned along the longitudinal direction of the fancy yarn. Values of the scanning are evaluated and the results of the evaluation are outputted. The results of the evaluation are the fancy yarn parameters such as base yarn mass, base yarn diameter, slub distance, mass increase of a slub, slub diameter increase, slub diameter, slub length and/or slub total mass. On evaluation, a measurement curve is produced from the values of the scanning, and an area (A(x)) between the measurement curve and a previously determined base yarn mass is computed. A permanent increase in the course of the area (A(x)) is used as a criterion for the presence of a slub. Slubs may be differentiated from yarn imperfections in a reliable manner by way of the area (A(x)).

FIELD OF THE INVENTION

The invention relates to a method for the characterization of fancy yarnIt may be applied in the textile laboratory (offline) as well as intextile production (online), e.g. in spinning works or winding works.

STATE OF THE ART

Fancy yarn is yarn whose structure or fiber composition differs from thenormal smooth yarn. It is applied in weaving mill products and knittingmill products as an enriching element. Fancy yarn usually has amultitude of thick places or thin places—so-called slubs—whose diameteris significantly larger or smaller than the diameters of the yarnsections lying between the slubs—the so-called base yarn. Structuredyarn with deliberately produced thickness variations with which no baseyarn may be identified is however also counted among the fancy yarns.The increasing popularity of fancy yarn demands reliable and meaningfulmethods for its characterization. Variables such as base yarn diameter,diameter increase at a slub, slub mass, slub length, slub distance, etc.are of particular interest. These variables may e.g. be used for thecontrol of the quality of the present fancy yarn or for determining themanufacturing parameters which are necessary for copying a given fancyyarn.

Methods and devices for characterization of yarn are known. They areusually based on a capacitive and/or optical scanning of the yarn movedin the longitudinal direction. The capacitive scanning principleprovides a signal corresponding to the yarn mass, whilst the opticalscanning principle provides a signal proportional to the yarn diameter.The scanning signal is evaluated in an analog or digital manner, and oneor several results of the evaluation are outputted. Examples of suchmethods and devices for the characterization of yarn are specified inthe patent publications EP-0'578'975 A1 or EP-0'249'741 A2. Both relateto the yarn testing system USTER®TESTER which is marketed worldwide bythe proprietor of the present protective property right.

It is also known to obtain information on the color, i.e. on thespectral reflection characteristics of yarn. Thus e.g. according toWO-2004/044579, one applies a multi-colored light source forilluminating the yarn. The light reflected by the yarn is detectedseparately in at least two different spectral ranges. The at least twodetection signals permit information with regard to the yarn color. Asimultaneous optical scanning of a textile material at differentwavelengths is also known from CH 674'379 or from DE-198'59'274.

WO-2005/071'150 A1, WO-2005/038'105 A1 and WO-2005/037699 A1 especiallydeal with fancy yarn. The teaching of the latter document may besummarized as follows:

-   -   determining the base yarn diameter: Firstly, the arithmetic mean        of the yarn diameter is formed over a large yarn length. This        mean is subtracted from the individual values of the yarn        diameter. The arithmetic means of all negative values which have        been measured adjacently to the other negative values is defined        as the base yarn diameter.    -   determining the beginning, end and length of a slub: A slub        beginning is present if a limit diameter which lies above the        base yarn diameter is overshot, and the overshoot persists over        a certain yarn length. A slub end is present if the limit        diameter is undershot, and the undershoot persists over a        certain yarn length. The slub length is defined as a distance        between the slub beginning and the slub end.    -   determining the slub diameter. A plurality of the largest        diameters is determined within a slub. The slub diameter is        defined as the mean of these largest diameters.

Although this teaching permits a useful characterization of fancy yarn,it also has a few disadvantages. A large quantity of data occurs as aresult, which is unclear and difficult to handle. Suitable possibilitiesfor the clear representation of the readings are not specified. Thedescribed method, if anything, results in a base yarn diameter which istoo large and in a slub length which is too small.

DESCRIPTION OF THE INVENTION

It is an object of the present invention to specify a method for thecharacterization of fancy yarn, which permits a reliable recognition ofthe slubs and their differentiation from yarn imperfections.

These and other objects are achieved by the methods defined in theclaims.

According to the method according to the invention, for thecharacterization of fancy yarn which preferably has a sequence of slubsand base yarn, at least one characteristic of the fancy yarn is scannedalong the longitudinal direction of the fancy yarn. Values of thescanning are evaluated and results of the evaluation are outputted.Results of the evaluation are outputted; it is preferably the case offancy yarn parameters such as base yarn mass, base yarn diameter, slubdistance, mass increase of a slub, slub diameter increase, slubdiameter, slub length and/or slub mass. With the evaluation, ameasurement curve is produced from the values of the scanning, and anarea below the measurement curve is computed. In a preferred embodiment,the area between the measurement curve and a previously determined baseyarn mass or a previously determined base yarn diameter is computed, anda permanent increase in the course of the area is used as a criterionfor the presence of a slub. Slubs may be reliably differentiated fromyarn imperfections by way of the area.

LISTING OF THE DRAWINGS

The invention is hereinafter described in more detail by way of thedrawings.

FIG. 1 schematically shows a device for carrying out the methodaccording to the invention.

FIG. 2 shows one example of a series of readings with regard to a fancyyarn, specifically yarn mass against length coordinate.

FIG. 3 shows a frequency distribution of the measured yarn mass plottedin FIG. 2.

FIG. 4 shows an enlarged section of FIG. 2.

FIGS. 5-15 show possible representation types according to theinvention, for outputting the yarn parameters.

FIG. 16 shows an example of a series of reading with regard to atwo-step fancy yarn, in the same representation as FIG. 2.

FIG. 17 shows one possible representation type according to theinvention, for outputting the characteristics of a multi-step yarn.

FIG. 18 shows a spectrogram of a series of readings with regard to afancy yarn.

FIG. 19 shows a measured and an idealized slub.

FIG. 20 shows a measurement curve with a thin place, analogous to FIG.4.

FIG. 21 shows the course of the area below a measurement curve, as afunction of the length coordinate.

FIG. 22 shows the mass per length unit as a function of tie lengthcoordinate, (a) for the measurement curve, (b) for an idealized curveand (c) for a curve which arises by subtraction of the curve (b) fromthe curve (a).

FIG. 23 shows spectrograms (a) of the curve of FIG. 22( a), (b) of thecurve of FIG. 22( b), and (c) of the curve of FIG. 22( c).

FIG. 24 show scatter diagrams (a) of the readings of FIG. 22( a), (b) ofthe slubs of FIG. 22( b), and (c) of the virtual base-yarn of FIG. 22(c).

IMPLEMENTATION OF THE INVENTION

A device 1 for carrying out the method according to the invention isshown schematically in FIG. 1. It contains a scanning unit 2 forscanning a fancy yarn 9 with base yarn 91 and slubs 92, 92′, which ismoved in a longitudinal direction -x. Here, the sequential recording ofa multitude of readings at different, preferably equidistant locationsof the fancy yarn 9 is to be understood under the term “scanning”. Suchscanning units 2 are known per se, and do not need to be explained inmore detail here. The scanning unit 2 may contain a capacitive, opticalor other sensor; also several equal or different sensors may be arrangedwithin the scanning unit 2. The scanning unit 2 may be provided withevaluation means for a preliminary evaluation of the readings. Itoutputs a preferably electrical output signal which is a measure for themass, the thickness or other characteristics of the fancy yarn 9, on afirst data lead 23. A3

The first data lead 23 runs into an evaluation unit 3 which is suitablefor evaluating the output signal of the scanning unit 2. For thispurpose, it contains suitable analog and/or digital evaluation means,e.g. a microprocessor. It may also contain further means such as memorymeans for storing data. The evaluation unit 3 is preferably a computer.

Furthermore, the device 1 contains an output unit 4 for outputtingmeasurement data and/or results of the evaluation. The output unit 4 isconnected to the evaluation unit 3 by way of a second data lead 34. Itmay e.g. be designed as a monitor and/or printer. The device 1preferably also contains an input unit 5 for inputting data on the partof the user. The input unit 5 may e.g. be a keyboard, a mouse and/or atouch screen.

FIG. 2 shows one possible output signal 100 of the scanning unit 2.Thereby, a variable for example which is a measure for the mass M perunit length of the fancy yarn 9 (see FIG. 1), is plotted along thelength coordinate x of the fancy yarn 9. Such a measure signal M istypically provided by a capacitive yarn sensor. A representation of thethickness of the fancy yarn 9 along the length coordinate x would appearin a similar manner, wherein the scales on the abscissa and the ordinateas well as the resolution could be different; a thickness signal istypically provided by an optical yarn sensor. The curve M(x) is notnecessarily continuous, but may be composed of individual (not shown inFIG. 2) scanning points which on the fancy yarn 9 are typicallydistanced from one another by a few millimeters; the distance depends onthe scanning rate of the scanning unit 2 and on the speed of the fancyyarn 9. The signal M(x) has a noise floor 101 which corresponds to thebase yarn mass M_(S) or the base yarn diameter. The peaks 102corresponding to the stubs project significantly from the noise floor101. A mean M_(M) of all readings M(x) over a large-yarn length, onaccount of the peaks 102, lies significantly above the noise floor 101and is therefore not suitable as a measure for the base yarn mass M_(S).At this location, it should be noted that FIG. 2 and the subsequentdiscussion only represents one possible, non-limiting example. Withother types of fancy yarn, it is no longer even possible to identifybase yarn.

The base yarn mass M_(S) may be determined according to the presentinvention preferably as follows. A frequency distribution H(M) of themeasured masses M represented in FIG. 2 is determined. Such a frequencydistribution H(M) is schematically shown in FIG. 3. The frequencydistribution H(M) must be determined for a large yarn length, underwhich here a yarn length is to be understood as one which contains mayslubs, for example at least 10 and preferably at least 100. Thefrequency distribution H(M) with an fancy yarn 9 comprises at least twolocal maxima 121, 122: a first local maximum 121 for the base yarn 91,and at least one second local maximum 122 for the slubs 92, 92′, . . . .According to definition, amongst all local maxima 121, 122, it is thelocal maximum 121 belonging to the base yarn 91 which has the smallestmass M. For this reason, the smallest mass M at which a local maximum121 occurs in the frequency distribution H(M) is defined as the baseyarn mass M_(S). The yarn number of the yarn body or of the base yarn 91may be computed from the base yarn mass M_(S). One may proceed in ananalogous manner in order to determine the base yarn diameter.

According to an alternative embodiment of the method according to theinvention for determining the base yarn mss, one defines a mass intervalI_(M) (see FIG. 3) which contains that smallest mass at which a localmaximum 121 occurs in the frequency distribution H(M). The mass intervalI_(M) may, but need not be symmetrical with respect to the “smallest”mass, i.e. the “smallest” mass may, but need not lie in the middle ofthe mass interval I_(M). The upper limit of the mass interval I_(M) ispreferably selected below the global mass mean M_(M). The width and theposition of the mass interval I_(M) may be predefined in a fixedmanner—for example ±5% of the “smallest” mass—automatically computed bythe evaluation unit 3, or be inputted by a user. A mean is subsequentlyformed over all masses M measured in this mass interval I_(M). The baseyarn mass is defined as this mean.

FIG. 4 shows a more detailed view of a section of the measurement curveM(x) of FIG. 2. Hereinafter, it is explained by way of FIG. 4 howfurther fancy yarn parameters such as slub length L_(E), slub distanceL_(S), mass increase ΔM and slub total mass M_(E) are evaluated.

For ascertaining a beginning 103 and end 104 of a slub 92, onepreviously determines a threshold value M_(T) which is larger than thebase yarn mass M_(S). The threshold value M_(T) may be predefined in afixed manner—for example 110% of the base yarn mass M_(S), automaticallycomputed by the evaluation unit 3 or inputted by a user. The beginning103 of a slub 92 is present if, proceeding from the noise floor 101, thethreshold value M_(T) is overshot. In order to exclude artifacts due tooutliers, one may additionally control as to whether the overshootpersists over a predefined yarn length, i.e. whether a few furthermeasurement points, which directly follow the measurement pointexceeding the threshold value M_(T), likewise lie above the thresholdvalue M_(T). In order to determine the beginning 103 of the slub 92 in amore accurate manner, one goes so far back on the measurement curve M(x)until, for the first time, a reading is smaller or equal to the baseyarn mass M_(S)—or another predefined or computed value. This reading isdefined as the beginning 103 of the slub 92. The end 104 of the slub 92is ascertained mutatis mutandis in an analogous method: on undershootingthe threshold value M_(T) proceeding from the signal peak 102, one movesso far forwards on the measurement curve M(x) until, for the first time,a reading is smaller or equal to the base yarn mass M_(S). If required,one may use different threshold values for determining the slubbeginning 103 and the slub end 104.

The slub length L_(E) according to the present invention is defined asthe distance between the beginning 103 and the end 104 of the slub 92.The slub distance L_(S) is defined as the distance between the end 104of a slub and the beginning 103′ of a subsequent slub 92′ to which asubsequent signal peak 102′ belongs. The distance between two adjacentslubs 92, 92′ is defined as the sum L_(E)+L_(S) of slub length and slubdistance. Typical slub lengths L_(E) and slub distances L_(S) lie in therange between 2 cm and a few meters.

The mass increase ΔM which corresponds roughly to a diameter increase ofthe fancy yarn 9 is defined in the simplest case as the differencebetween a local maximum 105 of the corresponding signal peak 102 and thebase yarn mass M_(S). Refined methods are possible for determining themass increase ΔM, which take account of the fluctuations of the scanningsignal M(x) along the slub length. Thus for example—analogously to theevaluation of the base yarn mass M_(S) described above—the most commonvalue within the corresponding slub length may be selected. A meanformation of values on the slub ridge is also considered. The massincrease ΔM is preferably specified as a multiple of the base yarn massM_(S), e.g. in percentage values, wherein the base yarn mass M_(S) ispreferably defined as 100%. Typical mass increases ΔM lie in a rangebetween 20% and 500%.

A further parameter for characterizing a slub 92 is the so-called slubtotal mass M_(E). This is essentially the difference between (i) theintegral of the measurement curve M(x) over the stub length L_(E) and(ii) the mass M_(S)·L_(E) of the yarn body on this slub length L_(E).The slub total mass M_(E) may be determined by calculation by theevaluation unit 3. The yarn number of the slub 92 may be computed fromthe fancy yarn mass M_(E), wherein the computation may contain adivision of the slub total mass M_(E) by the slub length L_(E).

The shape of a slub 92 may also be determined and outputted. Thereby,one may fall back on a comparison with simple geometric shapes such as abar, triangle, step, trapezium, or bell; cf. FIG. 18. The respectiveshape may e.g. be outputted on the output unit 4.

Not only are “local” parameters of the individual slubs of interest, butalso “global” parameters of a whole yarn section, of a yarn or of agroup of several yarns. Such a global fancy yarn parameter is theaverage yarn number (average yarn mass), which may be computed forexample by way of mean formation over all readings. The yarn number ofall base yarn 91 may also be of interest. A further global fancy yarnparameter is the average spatial frequency of the slubs, i.e. theaverage number of slubs per length unit.

The fancy yarn parameters mentioned above, and possible further ones arepreferably determined dynamically during a running time of the scanning.The slub parameters are stored for the purpose of outputting. It isadvantageous to additionally store a continuous running number allocatedto the respective stub, in order not only to be able to provideinformation on the individual slubs, but also on their sequence.

It may be advantageous to equip the scanning unit 2 (FIG. 1) with acapacitive as well as an optical yarn sensor which may simultaneouslymeasure one and the same yarn. The output signals of the capacitive andof the optical sensor may be linked to one another in a suitable mannerfor the purpose of an improved or more accurate evaluation. Capacitivemeasurement has the advantage that it provides a signal with a goodsignal-to-noise ratio. The signal however is proportional to the massper length unit, and thus does not correspond to the visual impressionof the yarn. This has a disadvantageous effect indeed with fancy yarnwhich in the region of a slub 92 often has a different yarn density thanin the region of a base yarn 91. Optical measurement has the advantageof better representing the visual impression of yarn, because itmeasures essentially the visible yarn diameter and it is thereforebetter suitable to fabric simulations. For this, the optical measurementsignal has a greater noise than the capacitive measurement signal. It ispossible by way of suitable linking of the two output signals, to profitfrom the advantages of both measurement types and to eliminate or atleast weaken their respective disadvantages.

Results of the evaluation may on the one hand be variables such as e.g.minima, maxima, arithmetic means and/or standard deviations of the abovedefined fancy yarn parameters. The number of slubs 92 per yarn lengthmay be a further variable of interest. These variables may be outputtedas alphanumeric signs. On the other hand, the results of the evaluationmay be graphically represented and outputted on the output unit 4 in asuitable manner. Preferred presentation types are shown in the FIGS.5-11.

One possible representation type is a histogram, i.e. the graphicrepresentation of the class frequencies of the classed yarn parameters.Three examples in the form of bar charts are specified in FIG. 5. Theordinate in each case is the frequency H. In FIG. 5( a) the massincrease ΔM, in FIG. 5( b) the slub length L_(E), and in FIG. 5( c) theslub distance L_(S) have been use as the abscissa. The abscissas mayhave a linear, logarithmic or other division. The division and/or scaleof the axes may be automatically computed or may be selected by way ofinput on the part of an operating person. The same applies to theselection of the classification, i.e. to the width of the classes. Notall classes necessarily need to have the same width.

The representation manner of FIG. 6 is a so-called scatter diagram(aggregate of plots). In this, the mass increase ΔM is: plotted againstthe slub length L_(E) for all stubs 92 of an fancy yarn 9 or a yarnsection. Each slub 92 is plotted as a point at the correct location.This representation simplifies the division of different slubs 92 intodifferent classes. Thus for example, it is immediately evident from FIG.6( a), that the examined fancy yarn 9 has three classes 111-113 orpopulations of slubs 92:

-   -   a first class 111 with short, low slubs    -   a second class 112 with long, low slubs, and    -   a third class 113 with long, high slubs.

An outlier analysis is carried out by way of the scatter diagram of FIG.6( a). For this purpose, one may provide a tool in order to define slubpopulations 111-113 and to the delineate them from one another as wellas from outliers. Such a tool may e.g. permit part surfaces 111.1-113.1of the scatter diagram to be defined on a monitor with a mouse, as isrepresented in FIG. 6( b). One slub population 111-113 is allocated toeach part surface 111.1-113.1. The part surfaces may e.g. be shaped as arectangle 111.1, as a circle 112.1 or a polygon 113.1. Points lyingoutside the part surfaces 111.1-113.1 are to be graded as outliers andwith further evaluations and/or representations, may be characterized assuch or not taken into account. If no part surfaces are defined, thenall points of the scatter diagram are counted as slubs and are treatedas such.

Other scatter diagrams are possible, for example slub total mass M_(E)against slub length L_(E), slub total mass M_(E) against mass increaseΔM, etc. The scatter diagram may be issued in a colored manner, whereindifferent colors may indicate different measurements, different pointdensities and/or populations or outliers (cf. FIG. 10). Athree-dimensional representation is analogously possible, in which twocoordinates correspond to those of FIG. 6, and the third coordinatecorresponds to the point density; cf. FIG. 9.

The scatter diagram may be represented for an individual fancy yarnsample or for several fancy yarn samples. In the latter case, one mayuse different colors for the different fancy yarn samples, in order todisplay possible differences between the samples. With several fancyyarn samples, one may display the result of the entirety of all fancyyarn samples additionally to the results of the individual fancy yarnsamples, preferably in a color which is individually allocated.

Apart from the actual values, one may also represent nominal values ornominal regions for one or more classes of slubs on the scatter diagram.The nominal and actual values may also be compared in otherrepresentation types, or in a purely numeric manner. Such nominal-actualcomparisons permit e.g. a control on the quality of a copy (actualvalue) or a predefined fancy yarn (nominal value).

The results may also be issued in the form of a table or aclassification matrix—as shown in FIG. 7, instead of a scatter diagram.The table axes correspond to the axes of the scatter diagram of FIG. 6.The numbers of respective slubs 92 are entered into the fields of thetables. Alternatively to the absolute number of slubs 92, one may alsoindicate their relative share; e.g. in percent or per thousand. Eachtable field thus represents a class of slubs 92, analogously to theclasses 111-113 which are described on the occasion of FIG. 6. Theselected size of the table fields is directed to the desiredclassification. With the selection of the size of the table fields, oneshould also take note that the resolution is sufficiently fine, but thatthe table still remains clear. In the example of FIG. 7, relativelysmall table fields were selected, which permit a finer classificationthan the three classes 111-113 which were described on the occasion ofFIG. 6. The table fields may be filled with colors, patterns or steps ofgray, which in turn are allocated to different numbers of slubs 92, forthe purpose of an improved visualization.

With the scatter diagram (FIG. 6) as well as the classification matrix(FIG. 7), the axes, independently of one another, may have a linear, alogarithmic or other division. The division and/or scale of the axes maybe computed automatically, or may be selected by way of input on thepart of the operating person. The same applies to the width and heightof the table fields in the classification matrix of FIG. 7, i.e. for theselection of the classification. FIG. 8 shows a further preferred outputpossibility for the determined fancy yarn parameters. It is the case ofa table which is subdivided into five main columns for the fiveparameters of slub length L_(E), slub distance L_(S), mass increase ΔM,diameter increase and number # of the slubs. The first four main columnsfor their part are subdivided in each case into three sub-columns forthe minimum Min, the mean Ø and the maximum Max of the respectiveparameter. The lines of the table may contain the values for the entireyarn or for the entire examined yarn section, as well as for theindividual slub populations 111-113. The minima L_(E,min), ΔM_(min), themeans L_(EØ), ΔM_(Ø) and the maxima L_(E,max), ΔM_(max) are indicatedfor the population 111 in FIG. 6( b). Of course, the table may also beformed in a different manner. In any case, such a tabular representationof the determined fancy yarn parameters leads to a reduction of data.Particularities of the fancy yarn concerned may be very quickly detectedand different fancy yarns may be easily compared by way of the table.

A further manner of representation for the results of the evaluation offancy yarn parameters is shown in FIG. 9. It is the case of a surface inthree dimensions (3D). Two of the three dimensions, the two horizontalaxes, correspond to the slub length L_(E) and the mass increase ΔM, asin the scatter diagram of FIG. 6. The third, vertical dimensionindicates the respective frequency H of the measured values, i.e. thepoint density in the scatter diagram of FIG. 6 or the numbers of FIG. 7.The 3D-surface which arises in this manner gives the impression of amountain [range] which permits a rapid and memorable visual perceptionof the peculiarities of the respective fancy yarn 9. It is particularlya synoptic comparison of two such “mountains” which very quickly showswhether the fancy yarn concerned has similar or differentcharacteristics, and in the latter case where the main differences lie.It is to be noted that the example of FIG. 9 relates to a differentfancy yarn than the example of FIG. 6. Whilst the fancy yarn of FIG. 6has three classes 111-113 of slubs 92, the fancy yarn of FIG. 9 only hastwo of them 114,115.

The three-dimensional representation manner of FIG. 9 may be reducedalso to two dimensions. FIG. 10 shows such a diagram which arises by wayof the projection of the “mountain” of FIG. 9 into the plane spanned bythe two horizontal axes L_(E), M. A “map” thus arises on which the“mountains” 114, 115 of FIG. 9 are represented by way of “altitudecontours”, i.e. lines of the same frequency H. Instead of “altitudecontours”, one may apply colors or cross-hatchings for rendering thedifferent frequencies H visible.

The representation types of the FIGS. 5-10 do not take into accountinformation on the sequence of the individual slubs. This information iscompletely present in the measurement series as is represented in FIG.2. It is possible from this to determine the respective yarn parametersuch as mass increase, slub length and slub distance as the measurementvariables (number value x unit), and to list these measurement variablesin the sequence of their occurrence, after one another. Such analphanumeric listing of the reduced measurement data may be useful forcertain cases, but is however less clear. Information on the sequence ofthe individual slubs is fully contained in the representation manner ofFIG. 11, wherein graphics have the advantage of an improved clarity andvisual perception compared to an alphanumeric value table. A horizontalbar is drawn in for each slub 92 and an adjacent base yarn 91. The baris composed of two parts. The length of a first, left part indicates therespective slub length L_(E), the length of a second, right partindicates the respective slub distance L_(S). The next bar lyingtherebelow characterizes the subsequent slub, etc. The horizontal barsof FIG. 11 may of course also be replaced by vertical columns.Measurement variables other than lengths L_(E), L_(S) may be plotted asbars, e.g. a slub mass and the associated base yarn mass, which may beadvantageous in particular with structured yarn with different base yarnmasses. it is also possible for a bar or column to indicate more thantwo slub parameters, e.g. with multi-step slubs (see FIG. 16) the firstslub length L_(E,1), the second slub length L_(E,2) and the associatedslub distance L_(S).

FIG. 12 shows a manner of representation which at least represents apart of the information on the sequence of the individual slubs in aclear manner. It is the case of a classification matrix which assumes aclassification of the slubs as has been implemented with the classes111-113, somewhat as in FIG. 6. In each case, a pair of two adjacentslubs 92, 92′ are considered, of which a first slub 92 is called a“leading slub” and a second slub 92′ a “trailing slub”. A correspondingentry into the classification matrix of FIG. 12 whose horizontal axisindicates the leading slub 92 and whose vertical axis indicates thetrailing slub 92′ is effected for each pair 92, 92′. One may deduce fromthe fictive example of FIG. 12, that in practice, two slubs of the firstclass 111 (cf. FIG. 6), and two slubs of the second class 112 are neversuccessive, but that a slub of the first class 111 often follows a slubof the second class 112, and a slub of the third class 113 very oftenfollows a slub of the first class 111.

Various slubs of a fancy yarn 9 may have different colors. For thisreason, it may be desirable to obtain information on the color of thefancy yarn 9. Suitable scanning units 2 and evaluation units 3 (seeFIG. 1) from the state of the art mentioned above are known for this.One possible representation manner for the obtained color information isshown in FIG. 13. Here it is the case of a circular chart whichindicates the measured shares of the differently colored slubs. In theexample of FIG. 13, the fancy yarn contains red (R) and blue (B) slubswhich occurred with a frequency of 45% and 55% respectively. Anenhancement to more than two colors is of course also possible. In thecase that the output unit 4 (see Fig. 1) permits a colored output, theindividual circle segments may be issued in the corresponding color. Apie chart is also possible instead of a circular chart

The circular chart of FIG. 13 contains no information on the sequence ofthe color stubs. This information is at least partly present in therepresentation manner of FIG. 14. Analogously to FIG. 12, in each casetwo successive slubs are considered, and the frequency of their colorsR, B is plotted in the table, wherein the horizontal table axisindicates the color R, B of the leading slub, and the vertical axisindicates the color R, B of the trailing stub. One may deduce from thetable of FIG. 14 that a color change often occurs in this fictiveexample, whereas two adjacent stubs having the same color is ratherrare.

The three-dimensional column charts of FIG. 15, by way of fictiveexamples, show how the color information may be combined with thegeometric information in a single representation manner. Thereby, thegeometric information lies in the plane of the drawing and correspondsto that of FIG. 5( a) and FIG. 5( b) respectively. The frequency ofclasses of the mass increase ΔM is plotted in the diagram of FIG. 15(a), and the frequency of classes of the slub length L_(E) is plotted inthe diagram of FIG. 15( b). The third dimension is used for the colorinformation R, B. One may deduce from the diagram of FIG. 15( a) thatthe red slubs R tend to have smaller mass increases ΔM than the bluestubs B. The diagram of FIG. 15( b) indicates that the red slubs R tendto be longer than the blue stubs B.

The FIGS. 5-15 discussed above only indicate a few example forrepresenting the fancy yam parameters of mass increase ΔM (or diameterincrease), stub length L_(E), slub distance L_(S) and color. One may ofcourse also graphically represent further relations between these andfurther fancy yarn parameters in a similar and two-dimensional orthree-dimensional manner.

Whilst single-step slubs have been discussed up to now, multi-step stubsare considered hereinafter. One example of a series of readings on atwo-step fancy yarn is specified in FIG. 16, in the same representationas FIG. 4. Here one may differentiate between a first stub step with afirst slub total mass M_(E,1) per length unit, a first mass increase ΔM₁and a first slub length L_(E,1), and a second slub step with a sectionstub total mass M_(E,2) per length unit, a second mass increase ΔM₂ anda second stub length L_(E,2). The mentioned parameters may be determinedin a manner which is analogous to that described for a single-step fancyyarn.

One possible manner of representation for the parameters of multi-stepfancy yarn is shown in FIG. 17. Here it is the case of a table whosehorizontal axis corresponds to the classed mass increase ΔM; cf. FIG. 5(a). The lines of the table represent the different steps of the fancyyarn. The respective frequencies are plotted in the fields of the table.The fancy yarn is two-step in the fictive example of FIG. 17, whereinthe second step occurs in two variants: with a relatively small massincrease ΔM₂ on the one hand, and with a relatively large mass increaseΔM₂ on the other hand. An analogous manner of representation is alsopossible for the stub length L_(E,2), L_(E,2). . . .

A further parameter of fancy yarn is the so-called pattern length. Thisis the length of the shortest sequence of stubs which are periodicallyrepeated in the fancy yarn. There is no periodicity whatsoever withinthis sequence, i.e. at least one slub parameter such as e.g. the stubdistance L_(S) is random or pseudo-random. The pattern length may beobtained e.g. by way of correlation computation from readings, as theyare represented for a short yarn section in FIG. 2. Such a correlationcomputation with all readings may be extensive with regard tocomputation. In order to reduce the computational effort, themeasurement data may be previously reduced in that e.g. the respectiveyarn parameters such as mass increase, stub length and stub distance aredetermined and the correlation computation is based on this reduceddata. In an analogous manner, one may also obtain information on thepresence of—mostly undesired—sub-patterns and their lengths. The patternlength and/or sub-pattern lengths are preferably issued in alphanumericor graphic form.

A spectrogram of the measurement signal M(x) of FIG. 2 may also provideuseful information on the fancy yarn. The measurement signal M(x) ispreferably subjected to a Fourier transformation for determining thespectrogram. One fictive example of a spectrogram |F{M}| or moreprecisely of the real part of the Fourier transform is shown in FIG. 18,wherein as is customary, a period length L is selected as the abscissa,preferably in a logarithmic scale. Usually, the spectrogram |F{M}|displays a relatively broad distribution 131 of the spatial frequenciesor of the period lengths L. One may deduce an average distance of theslubs from the position of the maximum 132. A pronounced peak in thespectrogram |F{M}| would indicate a —mostly undesired—periodicity in thefancy yarn. The periodicity on the one hand may relate to the individualstubs. With a fancy yarn with a constant slub distance L_(E)+L_(S),within which the slub length L_(E) and the slub distance L_(S) vary, themaximum 132 appears as a pronounced peak. In order to ascertain this, ayarn length of at least ten, preferably one hundred and more slubdistances should be measured. The periodicity on the other hand mayrelate to the patterns. With a sufficiently long measurement series—atleast ten, but preferably one hundred and more pattern lengths—one mayalso read out the pattern length from the position of a respective peak133 in the long-waved region of the spectrogram |F{M}|.

A further graphic representation manner for the stubs is a smoothed oridealized representation of the readings, as is shown in FIG. 19. On theone hand, the readings of FIG. 4 are drawn in a dotted manner. On theother hand, an idealized course of the measurement curve is indicatedwith an unbroken line. As the man skilled in the art knows, there aremany possibilities of obtaining an idealized curve in the manner of FIG.19 from a real measurement curve. In the application example of FIG. 19,base yarn 91, 91′ have been approximated by horizontal straight lineswhich all lie at the height of the previously determined base yarn massM_(S). One slub 92 is idealized in each case as a trapezium with flanks93, 94 and a horizontal roof 95. Thereby, the trapezium does notnecessarily need to be symmetrical, i.e. the flanks 93, 95 with regardto magnitude may also have different gradients. The approximation of theslub 92 by a trapezium may be effected according to methods and criteriaknown to the man skilled in the art. The flanks 93, 94 may roughly bestraight lines whose positions have been determined by way of the methodof least squares, or in another manner. The height of the trapezium,i.e. the position of the roof 95, may be determined according to thecriterion that the area of the trapezium is equal to the area below thereal measurement curve. The slub length L_(E) may for example be definedas the base length of the trapezium, i.e. as the distance between a slubbeginning 103* and a slub end 104*, wherein the slub beginning 103* andthe slub end 104* are the intersection points of the horizontalrepresenting the base yarn mass M_(S) and the left flank 93 or the rightflank 94. Alternatively, the slub length L_(E) may be may be defined asthe width of the trapezium at half the height, which is equal to halfthe sum of the base length and the roof length. The mass increase ΔM maybe defined at the height of the trapezium, i.e. as the distance betweenthe base and the roof. Under certain circumstances, the trapezium maydegenerate into the special case of a triangle (trapezium with a rooflength equal to zero) or of a rectangle (trapezium all with rightangles). Other shapes for the idealized measurement curve are likewisepossible. Such idealized courses of curves permit an improved visualperception of the characteristics of the fancy yarn. Parameters of theidealized curve, such as e.g. height, base length, roof length, the slublength L_(E) or the flank gradients of tie trapezium may be outputted ascharacteristic variables in a table for example, and be used for furtherevaluations. The output of such variables leads to a reduction in thedata.

An incomplete manufacturing process for the fancy yarn may lead to athin place 106 being present directly next to a slub 102, as indicatedin FIG. 20. Such undesired thin places 106 may be detected according tothe present invention. Their number or share with regard to quantity atthe slubs 102 may be outputted as a result. A thin place share of 50%means that a thin place 106 was observed next to half of all slubs 106,which indicates a deficient manufacturing process.

Spinning works which manufacture fancy yarn have the need todifferentiate between the following two phenomena:

-   -   on the one hand, the virtual base yarn manufacture, which may        introduce imperfections, irregularities and faults such as thick        places or thin places into the yarn, and    -   on the other hand, the slub manufacture which incorporates the        desired slubs onto the virtual base yarn, e.g. in the form of        thickenings.

These two phenomena are sometimes impossible or difficult todifferentiate with conventional yarn testing methods and apparatus. Theexemplary curve of FIG. 4 was selected for didactic reasons, so that itis quite clear from this, what a slub 102 is and what a base yarn 101is. In practice however, the undesired thickness fluctuations on diebase yarn 101 may be so large, that they exceed the threshold valueM_(T) and as a result are wrongly considered to be a slub on evaluation.The results of the evaluation are therefore adulterated. The results ofthis may lead to the wrong measures being taken in the manufacturingprocess. If e.g. long thick places or yarn mass fluctuations are assumedto be small slubs, the part process for slub manufacture is changed suchthat larger slubs may be produced. This measure unnecessarily changesthe slub structure without alleviating the actual cause of thefault—perhaps a defect in one path.

Here, a preferred embodiment solves this problem by way of specifyingthe definition of a slub. The method described on the occasion of FIG. 4may be disadvantageous since on setting the threshold value M_(T), itonly takes into account a one-dimensional mass increase. As described,although one may attempt to reduce this disadvantage by way of thedemand that the excess must last for a certain length. This however alsodoes not lead to an optimal recognition of the slubs. The observation ofan area below the measurement curve—or what is considered here as beingequivalent to the area, a certain integral of the measurement curve, hasbeen shown to be more advantageous. Such an area may be computed atleast approximately with one of the known numeric integration methods,like with the rectangle or trapezium method. FIG. 21 schematically showsa typical course of the area A(x) computed in this manner, as a functionof the length coordinate x, wherein the previously determined base yarnmass M_(S) (see FIG. 4) serves as basis for determining the area. Thevalues of A(x) fluctuate around the value zero in the region of the baseyarn 101. Any thick places, even if they have a large mass increase, donot cause any significant area changes, since they only extend in eachcase over a short length interval. A real slub 92 differs from a thickplace in that it causes a significant rise of the curve A(x) which setsin at the beginning of a slub 102. A local maximum 105 of the slub 92which may also be described as the position of the slub 92, is locatedat the turning point of the curve A(x). After the slub end 104, thecurve A(x) again fluctuates around a constant value, which indicates theslub total mass. If one ascertains such a slub end 104, then the furthercourse of the curve may be set back to the value zero by way ofsubtraction of the value M_(E). A further base yarn follows etc. Allslubs and their positions may be recognized in a reliable and stablemanner and be differentiated from thick places by way of this.

The ascertaining of a slub is preferably made dependent on thesimultaneously fulfillment of several criteria, e.g. of the followingthree criteria:

-   (i) exceeding a predefined threshold value for the area A(x),-   (ii) exceeding a predefined threshold value for the slub length    L_(E), and-   (iii) exceeding a predefined threshold value for the mass increase    ΔM.

Only when these criteria are simultaneously fulfilled may one reliablyassume that a proper slub and not a yarn imperfection is present.

The differentiation between the virtual base yarn and slubs issimplified even greater by way of a further embodiment of the methodaccording to the invention. According to this embodiment, the idealizedcourse of the curve according to FIG. 19 is subtracted from the realmeasurement curve. This is schematically represented in FIG. 22. Inthis, FIG. 22( a) shows the curve of the original readings, FIG. 22( b)the idealized curve (cf. FIG. 19), and FIG. 22( c) the curve whicharises when one subtracts the idealized curve from the originalmeasurement curve. The curve of FIG. 22( b) shows only the (idealized)slubs, the curve of FIG. 22( c) only the virtual base yarn withoutslubs. These representations alone may contribute to a deeperunderstanding of the structure of the examined fancy yarn. The dataobtained in this manner may however be evaluated even further, as isdiscussed hereinafter.

FIG. 23 schematically shows results of an evaluation of the data of FIG.22 in a spectrogram, i.e. in a representation which corresponds to thatof FIG. 18. FIG. 23( a) shows the spectrogram of the original readings,i.e. the curve of FIG. 21( a). As already indicated above, it isdifficult or even impossible to differentiate between stubs and virtualbase yarn only by way of this spectrogram. The representations of theFIGS. 23( b) and (c) alleviate this problem. FIG. 23( b) shows thespectrogram of the slubs alone, i.e. of the curve of FIG. 22( b). Thisdata related to the slub permits malfunctioning in the slub productionto be localized and overcome in a targeted manner, or permits the slubproduction to be changed in a targeted manner. Peaks in the long-wavedregion may e.g. indicate undesired periodicities, which may be avoidedwith suitable measures. FIG. 23( c) shows the spectrogram of the virtualbase yarn, i.e. of the curve of FIG. 22( c). Any peaks in thisspectrogram give good hints as to certain faults in the spinningprocess, or in the process stages preceding the spinning process, suchas eccentricities of certain rollers in the drawing arrangement. Thesefaults may be localized by way of the respective wavelengths in thespectrogram of FIG. 23( c), and subsequently dealt with.

The data of FIG. 22 may just as easily be represented in a scatterdiagram, analogously to FIG. 6. This form of representation may also bevery useful in order to differentiate between slubs and the virtual baseyarn. A schematic example is specified in FIG. 24. FIG. 24( a) shows ascatter diagram of the original readings of the curve of FIG. 22( a).Here, three phenomena intermingle:

-   -   the lesser disturbing thick places occurring in each yarn,    -   slubs and    -   thick places wrongly evaluated as slubs.

FIG. 24( b) shows a scatter diagram of the slubs on their own, as theyare represented in FIG. 22( b). In particular, when the robust methodfor slub recognition described on the occasion of FIG. 21 is used, thisscatter diagram will have no points which undesirably originate fromimperfections such as thick places. Rather it only contains real slubs.FIG. 24( c) shows a scatter diagram of the virtual base yarn of FIG. 22(c). The points drawn therein do not represent slubs, but imperfectionssuch as thick places. The scatter diagram of FIG. 24( c) may provideinformation on the applied yarn manufacturing process.

Other representation types such as e.g. the histograms of FIG. 5 may beused separately in an analogous manner for the data related on the onehand to the slub, and for tile data related on the other hand to thevirtual base yarn.

It may be advantageous in the method according to the invention tofilter the readings as are represented somewhat in FIG. 2 or 4,according to certain filter criteria Such filter criteria may forexample be the following:

-   -   yarn imperfections such as neps, thick-and/or thin places. Thus        for example, it is known from CH-678'173 A5 or from U.S. Pat.        No. 5,537,811 A, to arrange possible yarn errors in a table in        the manner of a coordinate system, for setting the clearing        limit of an electronic yarn cleaner. The abscissa of the        coordinate system represents the error mass and the ordinate        represents the error length. An upper and a lower clearing limit        are applied in this coordinate system. Neps and thick places        above the upper clearing limit, and thin places below the lower        clearing limit are automatically removed from the yarn. One may        proceed in an analogous manner also with the method according to        the invention by way of defining at least one “clearing limit”.        Thick or thin places within this limit are filtered out and only        slubs outside this limit are evaluated further and/or        represented graphically.    -   Slub characteristics. Thus e.g. slubs which fall short or exceed        a certain slub length L_(E), which fall short or exceed a        certain slub total mass M_(E), which have or do not have a        certain slub shape (cf. FIG. 19) etc. may be filtered out. Only        the remaining slubs which are not filtered out are evaluated        further and/or graphically represented. It is also possible to        provide several different filters, so that for example, with a        first filter, only short slubs, and with a second filter, only        long slubs are able to be evaluated and/or graphically        represented.

The method according to the invention preferably permits an interactiveinput of certain parameters on the part of an operating person. Suchparameters to be inputted may be filter parameters for the filtersdiscussed above. The basics for the evaluation may also be inputted asparameters, thus e.g. a defined base yarn mass M_(S).

In the method according to the invention, it may be advantageous toprovide an interface for outputting data which has been obtained in themethod. Such data may e.g. be the fancy yarn parameters discussed above,which are transferred to simulation software. From this, the simulationsoftware may be a simulation of the examined yarn of a sheet formationwoven or knitted from the yarn. Such a simulation based on evaluationdata is comparatively quick and simple compared to a simulation based onmeasurement data.

Of course, the present invention is not limited to the embodimentsdiscussed above. The man skilled in the art, with the knowledge of theinvention, is capable of deriving further variants which also belong tothe subject-matter of the present invention. Individual features of themethod according to the invention, which are described above, inparticular the evaluation algorithms for the individual fancy yarnparameters, may also be applied detached from the graphic representationaccording to the invention. Although the present description isconcentrated on the example of the capacitive measurement of the yarnmass, the invention is not limited to this scanning principle. Indeed,other scanning principles—possibly with other measurement variables—maybe applied with the method according to the invention, e.g. the opticalmeasurement of the yarn diameter. Combinations of different scanningprinciples are also possible.

LIST OF REFERENCE NUMERALS

-   1 device-   2 scanning unit-   23 first data lead-   3 evaluation unit-   34 second data lead-   4 output unit-   5 input unit-   9 fancy yarn-   91, 91′ base yarn-   92, 92′ slub-   93, 94 slub flanks-   95 slub roof-   100 measurement curve-   101 noise floor-   102, 102′ signal peak-   103, 103′, 103* slub beginning-   104, 104* slub end-   105 local maximum of a peak-   106 thin place next to slub-   111-115 classes of slubs, slub populations-   111.1-113.1 part areas of the scatter diagram-   121 local maximum which belongs to the base yarn-   122 local maximum which belongs to the slubs-   131 distribution in the spectrogram-   132 maximum of the distribution 121-   133 peak in the spectrogram-   A area below the measurement curve-   B color blue-   H frequency of a reading-   I_(M) mass interval-   L period length-   L_(E) slub length-   L_(S) slub distance-   L_(E)+L_(S) slub distance-   M mass per length unit-   M_(E) slub total mass-   M_(M) mean of the measured mass per length unit-   M_(S) base yarn mass per length unit-   M_(T) threshold value-   R color red-   x length coordinate-   ΔM mass increase of a slub.

1. A method for the characterization of fancy yarn, the methodcomprising the steps of: scanning at least one characteristic of thefancy yarn along a longitudinal direction of the fancy yarn, evaluatingvalues of the at least one characteristic, wherein a measurement curveis produced from the values, an area below the measurement curve iscomputed, and a permanent increase in a course of the area is used as acriterion for determining a slub, and outputting results.
 2. The methodaccording to claim 1, wherein an area between the measurement curve andat least one of a previously determined base yarn mass and a previouslydetermined base yarn diameter is computed.
 3. The method according toclaim 1, wherein a determination of a slub is made dependent on asimultaneous fulfillment of several criteria.
 4. The method according toclaim 3, wherein criteria for determining a slub are selected from thegroup comprising: (i) overshooting a defined threshold value for acourse of the area below the measurement curve, (ii) overshooting adefined threshold value for a length of the slub, and (iii) overshootinga defined threshold value for a mass increase.
 5. The method accordingto claim 1, wherein the at least one scanned characteristic is at leastone of a mass and a diameter of the fancy yarn.
 6. The method accordingto claim 1, wherein the results are selected from the group of fancyyarn characteristics that includes a base yarn mass, a base yarndiameter, a slub distance, a mass increase of a slub, a slub diameterincrease, a slub diameter, and slub length, a slub total mass, anaverage yarn number, a number of slubs per length unit, a patternlength, a sub-pattern length, a shape, and a color.
 7. The methodaccording to claim 6, wherein a smallest mass and a smallest diameter atwhich in a frequency distribution of masses and diameters respectively,measured over a large yarn length, a local maximum occurs, is defined asa base yarn mass and as a base yarn diameter respectively.
 8. The methodaccording to claim 6, wherein for determining the base yarn mass and thebase yarn diameter, an interval is defined that contains a smallest massand a smallest diameter at which in a frequency distribution of massesand diameters respectively, measured over a large yarn length, a localmaximum occurs, and the base yarn mass and the base yarn diameter isdefined as an average value over all masses and diameters respectively,measured in the interval.
 9. The method according to claim 6, whereinthe slub length is defined as a distance between a beginning and an endof a slub.
 10. The method according to claim 6, wherein the slubdistance is defined as a distance between a trailing end of a precedingslub, and a leading end of a subsequent slub.
 11. The method accordingto claim 6, wherein the slub total mass is defined as a differencebetween an integral of the measurement curve over the slub length, and amass of a body of the fancy yarn on the slub length.
 12. The methodaccording to claim 6, wherein a running number is associated with eachslub, and the running number is stored together with parameters of theassociated slub.
 13. The method according to claim 6, wherein theresults include at least one of minima, maxima, arithmetic means, andstandard deviations of the fancy yarn characteristics, and a number ofslubs per yarn length.
 14. The method according to claim 1, wherein thefancy yarn is scanned at least one of capacitively and optically. 15.The method according to claim 14, wherein the fancy yarn is scannedcapacitively and optically, and output signals of the capacitive and theoptical scanning are linked to one another.
 16. The method according toclaim 1, wherein at least one result of the evaluation is outputted inthe form of a graphic representation.
 17. The method according to claim16, wherein the graphic representation is selected from a group ofdiagrams consisting of (1) a recording of a scanned fancy yarncharacteristic with respect to at least one of a position on the fancyyarn and time, (2) a histogram, (3) a two-dimensional column chart, (4)a three-dimensional column chart, (5) a two-dimensional bar chart, (6)three-dimensional bar chart, (7) a scatter diagram, (8) a classificationmatrix, (9) a surface in a three-dimensional representation, (10) asurface in a two-dimensional representation, (11) a column chart, (12) acircular chart, (13) a pie chart, (14) a table, and (15) a spectrogram.18. The method according to claim 16, wherein different populations ofslubs are identified using the graphic representation.
 19. The methodaccording to claim 1, wherein the step of evaluating includes at leastone of smoothing and idealization of the values.
 20. The methodaccording to claim 19, wherein the step of evaluating includes linkingat least one of the smoothed and idealized values with associated valuesthat have not been smoothed and idealized.
 21. The method according toclaim 20, wherein the linking is at least one of a difference formationand a quotient formation.
 22. The method according to claim 19, whereinthe at least one of smoothing and idealization includes an approximationby straight stretch sections, and slubs of the fancy yarn areapproximated as at least one of trapezoids, triangles and rectangles.23. The method according to claim 1, wherein the step of evaluatingincludes filtering the values.
 24. The method according to claim 1,wherein at least one parameter used in the evaluating step is input inan interactive manner.
 25. The method according to claim 19, wherein anindividual graphic representation for the at least one of smoothed andidealized values is outputted.
 26. The method according to claim 20,wherein an individual graphic representation for data produced by thelinking step is outputted.